1. Field of the Invention
The present invention relates to a grate for incineration plants for the incineration of combustible material, in particular refuse, comprising at least one grate track, which is composed of fixed and movable grate-lining rows, which are arranged alternately in the direction of flow of the combustible material and have a number of grate-lining units lying side by side, the grate-lining units being connected in the region of their rear end to fixed and movable grate-lining carriers respectively and moving with their front end on or over the following grate-lining unit, and a drive being assigned to the movable grate-lining units.
2. Discussion of Background
Firing grates serve to incinerate combustible material and at the same time transport it further. In particular for incineration plants for refuse, forward-feed, reversed-feed and opposed overfeed grates having fixed and movable grate-lining units are known. The movement of the movable grate-lining rows is effected essentially by virtue of the fact that a plurality of rows of grate-lining units are combined and are actuated by a single drive. It would be expensive to move each row individually (K. J. Thome-Kozmiensky: Thermische Abfallbehandlung. EF-Verlag fur Energie- und Umwelttechnik GmbH, 2nd edition, 1994, pages 156-159).
Thus, for example in DE-B 25 47 155, the movable elements of the grate-lining drives are arranged in the region of the underblast. The result of all this is that the possible movements of the grate-lining units are greatly restricted and thus ideal adaptation to the burn-up behavior of the combustible material cannot be achieved. Due to a plurality of moving grate-lining rows being combined in terms of the drive, the grate cannot be subdivided into a sufficient number of air zones (underblast zones, i.e. chambers which are arranged under the grate lining and through which some of the combustion air and, in the case of air-cooled grates, the cooling air is supplied to the grate-lining units) in order to react in an optimum manner to the various firing states on the grate.
According to CH 637 198, in order to adapt the movement of the movable grate-lining rows to the burnup behavior of the combustible material, a drive which has a pivoted linkage having a pivotable torsion bar led out of the underblast region is used for the grate, the pivoted linkage being arranged with the drive outside the underblast region. In this case, a rectilinear-guide device is assigned to the torsion bar and causes additional translational motion of the torsion bar, this translational motion permitting a linear movement of the grate-lining units. A disadvantage with this prior art is that the solution is relatively complicated, since multiple weight transfer has to be effected.
To incinerate refuse having a high calorific value, water-cooled grate systems (EP 0 757 206 A1, EP 0 844 438) are used, so that the useful life of the grate-lining units is not reduced on account of the high thermal loading. The attachment of the supply and discharge hoses for the liquid cooling medium causes very restricted space conditions. Since the hoses perform up to 5.times.10.sup.5 movements per year, leakages often occur. In addition, liquid metals damage the supply and discharge hoses of the cooling medium, and a build-up occurs, which together with the aggressive atmosphere reduces the plant availability. If, in the event of a cooling-hose leakage, a refuse-incineration plant is not shut down for reasons of cost, an acute personnel hazard has to be tolerated during the removal of the leakage.